Method and apparatus for calibrating transmit power of a femto node

ABSTRACT

Methods and apparatuses are provided that include calibrating transmit power of a femto node based on measuring one or more parameters related to usage of the femto node. The femto node can temporarily increase transmit power and analyze received measurement reports to determine a transmit power calibration. The femto node can additionally measure uplink received signal strength indicators over multiple time periods following handover of a user equipment (UE) to determine whether to increase transmit power to cover the UE.

CROSS-REFERENCE TO RELATED APPLICATIONS

The Application for Patent is a Divisional Application of U.S. patentapplication Ser. No. 13/450,949, entitled “METHOD AND APPARATUS FORCALIBRATING TRANSMIT POWER OF A FEMTO NODE,” which was filed Apr. 19,2012, and claims priority to Provisional Application No. 61/477,945,entitled “METHOD AND APPARATUS FOR ESTIMATING HOME USER USAGE ATFEMTOCELLS” filed Apr. 21, 2011, assigned to the assignee hereof. Theaforementioned applications are herein incorporated by reference intheir entirety.

BACKGROUND

Field

The following description relates generally to wireless networkcommunications, and more particularly to determining usage at a femtonode.

Background

Wireless communication systems are widely deployed to provide varioustypes of communication content such as, for example, voice, data, and soon. Typical wireless communication systems may be multiple-accesssystems capable of supporting communication with multiple users bysharing available system resources (e.g., bandwidth, transmit power, . .. ). Examples of such multiple-access systems may include code divisionmultiple access (CDMA) systems, time division multiple access (TDMA)systems, frequency division multiple access (FDMA) systems, orthogonalfrequency division multiple access (OFDMA) systems, and the like.Additionally, the systems can conform to specifications such as thirdgeneration partnership project (3GPP) (e.g., 3GPP LTE (Long TermEvolution)/LTE-Advanced), ultra mobile broadband (UMB), evolution dataoptimized (EV-DO), etc.

Generally, wireless multiple-access communication systems maysimultaneously support communication for multiple mobile devices. Eachmobile device may communicate with one or more base stations viatransmissions on forward and reverse links. The forward link (ordownlink) refers to the communication link from base stations to mobiledevices, and the reverse link (or uplink) refers to the communicationlink from mobile devices to base stations. Further, communicationsbetween mobile devices and base stations may be established viasingle-input single-output (SISO) systems, multiple-input single-output(MISO) systems, multiple-input multiple-output (MIMO) systems, and soforth.

To supplement conventional base stations, additional restricted basestations can be deployed to provide more robust wireless coverage tomobile devices. For example, wireless relay stations and low power basestations (e.g., which can be commonly referred to as Home NodeBs or HomeeNBs, collectively referred to as H(e)NBs, femto nodes, pico nodes,etc.) can be deployed for incremental capacity growth, richer userexperience, in-building or other specific geographic coverage, and/orthe like. Such low power base stations can be connected to the Internetvia broadband connection (e.g., digital subscriber line (DSL) router,cable or other modem, etc.), which can provide the backhaul link to themobile operator's network. Thus, for example, the low power basestations can be deployed in user homes to provide mobile network accessto one or more devices via the broadband connection.

Such low power base stations can calibrate power based on sensingsurrounding radio frequency conditions and/or obtaining channelconditions from served UEs via measurement reports. Such powercalibration, however, may not be sufficient to operate a low power basestation in a desired manner, such as for providing a desired coveragearea within boundaries of an area (e.g., within walls or floors of ahome or office, etc.), since only potential interference to other nodesor devices is considered.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

In accordance with one or more aspects and corresponding disclosurethereof, the present disclosure describes various aspects in connectionwith calibrating power of a femto node based in part on inferring ormeasuring usage parameters for devices served by the femto node. In oneexample, the femto node can increase a coverage area during a call, anddetermine usage parameters during this time based on channel conditionreports received by the device. In another example, the femto node cansimilarly increase coverage area and collect measurement reports fromvarious devices (e.g., served or non-member devices), and can calibratea transmission power to provide support for served device whileminimizing interference to non-member devices. In yet another example,the femto node can evaluate a received signal strength followinghandover of a device to determine whether the device is leaving vicinityof the femto node, or staying within the vicinity but just out of rangeof the femto node. The femto node can calibrate transmission power basedon this evaluation.

According to an example, a method for calibrating transmission power ofa femto node is provided. The method includes increasing a transmitpower of a femto node from a base transmit power for a duration of timeand receiving one or more measurement reports from one or more userequipments (UEs) during the duration of time. The method furtherincludes calibrating the base transmit power of the femto node based inpart on the one or more measurement reports and the increased transmitpower.

In another aspect, an apparatus for apparatus for calibratingtransmission power of a femto node is provided. The apparatus includesat least one processor configured to increase a transmit power of afemto node from a base transmit power for a duration of time and receiveone or more measurement reports from one or more UEs during the durationof time. The at least one processor is further configured to calibratethe base transmit power of the femto node based in part on the one ormore measurement reports and the increased transmit power. The apparatusfurther includes a memory coupled to the at least one processor.

In yet another aspect, an apparatus for calibrating transmission powerof a femto node is provided. The apparatus includes means for increasinga transmit power of a femto node from a base transmit power for aduration of time and means for receiving one or more measurement reportsfrom one or more UEs during the duration of time. The apparatus furtherincludes means for calibrating the base transmit power of the femto nodebased in part on the one or more measurement reports and the increasedtransmit power.

Still, in another aspect, a computer-program product for calibratingtransmit power of a femto node is provided including a non-transitorycomputer-readable medium having code for causing at least one computerto increase a transmit power of a femto node from a base transmit powerfor a duration of time. The computer-readable medium further includescode for causing the at least one computer to receive one or moremeasurement reports from one or more UEs during the duration of time andcode for causing the at least one computer to calibrate the basetransmit power of the femto node based in part on the one or moremeasurement reports and the increased transmit power.

Moreover, in an aspect, an apparatus for calibrating transmission powerof a femto node is provided that includes a power adjusting componentfor increasing a transmit power of a femto node from a base transmitpower for a duration of time and a measurement report receivingcomponent for receiving one or more measurement reports from one or moreUEs during the duration of time. The apparatus further includes a powercalibrating component for calibrating the base transmit power of thefemto node based in part on the one or more measurement reports and theincreased transmit power.

According to an example, a method for calibrating transmission power ofa femto node is provided. The method includes detecting a handover of aserved UE from a femto node to another node and measuring an uplinkreceived signal strength indicator (RSSI) at the femto node over aplurality of time periods based on the detecting the handover. Themethod further includes calibrating a transmit power of the femto nodebased on comparing the uplink RSSI measured over the plurality of timeperiods.

In another aspect, an apparatus for apparatus for calibratingtransmission power of a femto node is provided. The apparatus includesat least one processor configured to detect a handover of a served UEfrom a femto node to another node and measure an uplink RSSI at thefemto node over a plurality of time periods based on the detecting thehandover. The at least one processor is further configured to calibratea transmit power of the femto node based on comparing the uplink RSSImeasured over the plurality of time periods. The apparatus furtherincludes a memory coupled to the at least one processor.

In yet another aspect, an apparatus for calibrating transmission powerof a femto node is provided. The apparatus includes means for detectinga handover of a served UE from a femto node to another node and meansfor measuring an uplink RSSI at the femto node over a plurality of timeperiods based on the detecting the handover. The apparatus furtherincludes means for calibrating a transmit power of the femto node basedon comparing the uplink RSSI measured over the plurality of timeperiods.

Still, in another aspect, a computer-program product for calibratingtransmit power of a femto node is provided including a non-transitorycomputer-readable medium having code for causing at least one computerto detect a handover of a served UE from a femto node to another node.The computer-readable medium further includes code for causing the atleast one computer to measure an uplink RSSI at the femto node over aplurality of time periods based on the detecting the handover and codefor causing the at least one computer to calibrate a transmit power ofthe femto node based on comparing the uplink RSSI measured over theplurality of time periods.

Moreover, in an aspect, an apparatus for calibrating transmission powerof a femto node is provided that includes a UE mode determiningcomponent for detecting a handover of a served UE from a femto node toanother node. The apparatus further includes a RSSI measuring componentfor measuring an uplink RSSI at the femto node over a plurality of timeperiods based on the detecting the handover and a power calibratingcomponent for calibrating a transmit power of the femto node based oncomparing the uplink RSSI measured over the plurality of time periods.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed aspects will hereinafter be described in conjunction withthe appended drawings, provided to illustrate and not to limit thedisclosed aspects, wherein like designations denote like elements, andin which:

FIG. 1 is a block diagram of an example wireless communication systemthat serves a user equipment (UE) using a femto node operating within apremises.

FIG. 2 is a block diagram of an example wireless communication systemfor expanding coverage of a femto node over a premises based onmonitoring one or more usage parameters.

FIG. 3 is a block diagram of an example usage map for a UE at a femtonode where the femto node does not cover an entire premises.

FIG. 4 is a block diagram of an example usage map for a UE at a femtonode where the femto node covers a premises.

FIG. 5 is a flow chart of an aspect of an example methodology forcalibrating power of a femto node.

FIG. 6 is a flow chart of an aspect of an example methodology forcalibrating power of a femto node based on received signal strengthindicator (RSSI) measurements.

FIG. 7 is a flow chart of an aspect of an example methodology foradjusting a transmit power based on a detected switch in communicationsmode of a UE.

FIG. 8 is a block diagram of a system in accordance with aspectsdescribed herein.

FIG. 9 is a block diagram of an aspect of a system that calibrates powerof a femto node based on temporarily increasing a transmit power.

FIG. 10 is a block diagram of an aspect of a system that calibratespower of a femto node based on RSSI measurements.

FIG. 11 is a block diagram of an aspect of a wireless communicationsystem in accordance with various aspects set forth herein.

FIG. 12 is a schematic block diagram of an aspect of a wireless networkenvironment that can be employed in conjunction with the various systemsand methods described herein.

FIG. 13 illustrates an example wireless communication system, configuredto support a number of devices, in which the aspects herein can beimplemented.

FIG. 14 is an illustration of an exemplary communication system toenable deployment of femtocells within a network environment.

FIG. 15 illustrates an example of a coverage map having several definedtracking areas.

DETAILED DESCRIPTION

Various aspects are now described with reference to the drawings. In thefollowing description, for purposes of explanation, numerous specificdetails are set forth in order to provide a thorough understanding ofone or more aspects. It may be evident, however, that such aspect(s) maybe practiced without these specific details.

As described further herein, a low power base station, or femto node,can calibrate transmission power based at least in part on one or moreaspects regarding user equipment (UE) served by the femto node. Forinstance, a femto node can determine or otherwise infer a usage patternof one or more UEs at the femto node to detect areas of a premisesrelated to the femto node for which coverage is not available. The femtonode can calibrate its transmit power in an effort to cover such areas.The areas can be inferred based in part on observing representativeparameters. In one example, a femto node can apply short term poweradjustments for at least pilot channel transmissions to facilitatedetermining such parameters. For instance, the femto node can extend acoverage area for one or more UEs by increasing power of a pilot channeltransmission when the UEs operate in an active mode (e.g., during acall). In this example, the femto node can determine power calibrationfor serving the UE based at least in part on receiving measurementreports from the UE during the period of active mode. For example, wherethe UE moves outside of a previous coverage area while in active mode,the femto node can determine to calibrate the transmit power based onmeasurement reports received while the transmit power is increased.

In another example, the femto node can increase transmit power of atleast the pilot transmissions to additionally capture registrations fromsurrounding UEs. In this example, the femto node can obtain measurementreports from served and/or non-member UEs, regardless of communicationsmode (e.g., idle or active) to determine a transmit power for adequatelyserving the served UEs without substantially interfering the non-memberUEs. In yet another example, the femto node can measure an uplinkreceived signal strength indicator (RSSI) as a previously served UEmoves away from femto node coverage. The RSSI values can be measured atvarious times to determine whether the UE is continually moving awayinto macro node coverage or whether the UE is in an area of coverage notserved by the femto node, but that may be part of an area of a premisesfor which femto node coverage is desired. Such mechanisms are used toestimate UE usage respective to a femto node, and can thus be used forimproving femto node calibration to improve UE communications with thefemto node.

A low power base station, as referenced herein, can include a femtonode, a pico node, micro node, home Node B or home evolved Node B(H(e)NB), relay, and/or other low power base stations, and can bereferred to herein using one of these terms, though use of these termsis intended to generally encompass low power base stations. For example,a low power base station transmits at a relatively low power as comparedto a macro base station associated with a wireless wide area network(WWAN). As such, the coverage area of the low power base station can besubstantially smaller than the coverage area of a macro base station.

As used in this application, the terms “component,” “module,” “system”and the like are intended to include a computer-related entity, such asbut not limited to hardware, firmware, a combination of hardware andsoftware, software, or software in execution, etc. For example, acomponent may be, but is not limited to being, a process running on aprocessor, a processor, an object, an executable, a thread of execution,a program, and/or a computer. By way of illustration, both anapplication running on a computing device and the computing device canbe a component. One or more components can reside within a processand/or thread of execution and a component may be localized on onecomputer and/or distributed between two or more computers. In addition,these components can execute from various computer readable media havingvarious data structures stored thereon. The components may communicateby way of local and/or remote processes such as in accordance with asignal having one or more data packets, such as data from one componentinteracting with another component in a local system, distributedsystem, and/or across a network such as the Internet with other systemsby way of the signal.

Furthermore, various aspects are described herein in connection with aterminal, which can be a wired terminal or a wireless terminal Aterminal can also be called a system, device, subscriber unit,subscriber station, mobile station, mobile, mobile device, remotestation, remote terminal, access terminal, user terminal, terminal,communication device, user agent, user device, or user equipment (UE),etc. A wireless terminal may be a cellular telephone, a satellite phone,a cordless telephone, a Session Initiation Protocol (SIP) phone, awireless local loop (WLL) station, a personal digital assistant (PDA), ahandheld device having wireless connection capability, a computingdevice, a tablet, a smart book, a netbook, or other processing devicesconnected to a wireless modem, etc. Moreover, various aspects aredescribed herein in connection with a base station. A base station maybe utilized for communicating with wireless terminal(s) and may also bereferred to as an access point, a Node B, evolved Node B (eNB), or someother terminology.

Moreover, the term “or” is intended to mean an inclusive “or” ratherthan an exclusive “or.” That is, unless specified otherwise, or clearfrom the context, the phrase “X employs A or B” is intended to mean anyof the natural inclusive permutations. That is, the phrase “X employs Aor B” is satisfied by any of the following instances: X employs A; Xemploys B; or X employs both A and B. In addition, the articles “a” and“an” as used in this application and the appended claims shouldgenerally be construed to mean “one or more” unless specified otherwiseor clear from the context to be directed to a singular form.

The techniques described herein may be used for various wirelesscommunication systems such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA and othersystems. The terms “system” and “network” are often usedinterchangeably. A CDMA system may implement a radio technology such asUniversal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includesWideband-CDMA (W-CDMA) and other variants of CDMA. Further, cdma2000covers IS-2000, IS-95 and IS-856 standards. A TDMA system may implementa radio technology such as Global System for Mobile Communications(GSM). An OFDMA system may implement a radio technology such as EvolvedUTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE802.16 (WiMAX), IEEE 802.20, Flash-OFDM®, etc. UTRA and E-UTRA are partof Universal Mobile Telecommunication System (UMTS). 3GPP Long TermEvolution (LTE) is a release of UMTS that uses E-UTRA, which employsOFDMA on the downlink and SC-FDMA on the uplink. UTRA, E-UTRA, UMTS,LTE/LTE-Advanced and GSM are described in documents from an organizationnamed “3rd Generation Partnership Project” (3GPP). Additionally,cdma2000 and UMB are described in documents from an organization named“3rd Generation Partnership Project 2” (3GPP2). Further, such wirelesscommunication systems may additionally include peer-to-peer (e.g.,mobile-to-mobile) ad hoc network systems often using unpaired unlicensedspectrums, 802.xx wireless LAN, BLUETOOTH and any other short- orlong-range, wireless communication techniques.

Various aspects or features will be presented in terms of systems thatmay include a number of devices, components, modules, and the like. Itis to be understood and appreciated that the various systems may includeadditional devices, components, modules, etc. and/or may not include allof the devices, components, modules etc. discussed in connection withthe figures. A combination of these approaches may also be used.

Referring to FIG. 1, an example wireless communication system 100 isillustrated that facilitates calibrating power of a femto node based onUE usage. System 100 comprises a base station 102 that implementscoverage area 104 for providing wireless network access to one or moreUEs. UEs within coverage are 104 can communicate with the base station102 using one or more wireless technologies to receive access to a corewireless network (not shown). Base station 102 can be a macro node,femto node, pico node, mobile base station, relay, UE (e.g.,communicating in peer-to-peer or ad-hoc mode with one or more UEs), aportion thereof, and/or substantially any device that can providewireless network access to one or more UEs. In addition, system 100includes a femto node 106 providing coverage area 108 within a premises110. For example, the femto node 106 can be substantially any low powerbase station, such as a H(e)NB, etc., that provides wireless networkaccess to one or more UEs, such as UE 112, based on restrictedassociation of the UEs to the femto node 106. For example, therestricted association can include a closed subscriber group (CSG)provided by the femto node 106, of which UE 112 is a member. Moreover,the premises 110 can include a structure, such as a home of a user, anoffice, and/or the like, or substantially any bounded physical area.Additionally, UE 112 can be a mobile terminal, a stationary device, amodem (or other tethered device), a portion thereof, and/orsubstantially any device that can receive wireless network access from abase station.

For example, as shown, the coverage area of the femto node 106 may notcover all areas of the premises 110. As described, current powercalibration mechanisms consider sensed radio frequency (RF) conditionsto calibrate power, and such a deficiency with respect to coverage thepremises 110 may result from using such mechanisms. In this case, UE 112can move from within coverage area 108 of femto node 106 inside thepremises 110, to outside of the coverage area 108 while within thepremises 110, in which case UE 112 connects to another base station,such as base station 102, for receiving wireless network access. Thisbehavior may not be desired of the femto node 106. Thus, as describedherein, femto node 106 can estimate or otherwise infer UE 112 or otherUE usage of femto node 106 in certain scenarios based on observing oneor more parameters to determine whether to expand coverage area 108 toimprove communications for UE 112 and/or other UEs.

In one example, where UE 112 is within coverage area 108 and establishesa call with another UE (e.g., voice call, data call, etc.) or isotherwise operating in an active communications mode, femto node 106 cantemporarily increase transmit power of at least a pilot channel to serveUE 112 in an extended coverage area. For example, femto node 106 canincrease the transmit power using a fixed increment, dynamic poweradjustment, adjustment based on a history of transmit power, and/or thelike. UE 112 can communicate measurement reports of channel conditionsto femto node 106 during the call in the extended coverage area. Femtonode 106 can accordingly calibrate transmit power, at least for an idlecommunications mode, based on the measurement reports to ensure coveragefor UE 112 in other areas of the premises 110 within which UE 112 waspresent and provided a measurement report. For example, femto node 106increases transmit power to ensure coverage for UE 112, and can computethe power calibration using the measurement reports, which can includedetermining a lowest measurement and a power necessary to ensure thelowest measurement is over a threshold to prevent handover of UE 112. Inanother example, femto node 106 can calibrate transmit power based oncomputing an average measurement of femto node 106 and selecting atransmit power to ensure the average measurement remains at least at athreshold, and/or the like.

In another example, femto node 106 can temporarily increase transmitpower while UE 112 is in idle mode, and can receive registrationattempts from UE 112, if UE 112 is operating outside of coverage area108, as well as other UEs that are within range of the extended coveragearea caused by the temporary increase in transmit power. In addition,the registration attempts can include measurement reports includingmeasurements of femto node 106 and/or another base station, such as basestation 102, at the UEs. In this regard, femto node 106 can calibratetransmission power based on the measurement reports and whether the UEsfrom which the measurement reports are received are members at femtonode 106 (e.g., members of a CSG provided by femto node 106). Forexample, femto node 106 can increase transmit power based on aregistration attempt and measurement report received from UE 112 whereUE 112 is outside of coverage area 108 but inside of the extendedcoverage area. In addition, where femto node 106 receives a registrationattempt and measurement report from another UE that is a non-member UEat femto node 106, femto node 106 can calibrate transmit power for UE112 while not causing substantial interference with the non-member UE(based on the measurement report therefrom).

In yet another example, femto node 106 can measure uplink (UL) RSSI, ora similar metric, when UE 112 is in a call to determine whether ahandout by UE 112 (e.g., to base station 102) is caused by UE 112leaving premises 110 or moving to a different area within the premises110 that is outside of coverage area 108. Femto node 106, in thisexample, can compare UL RSSI reports after handover of UE 112 to basestation 102 to determine whether the RSSI decreases, and/or an amount ofdecrease, over a period of time. For instance, a UE moving outside ofpremises 110 can correlate to a steadily decreasing UL RSSI, as opposedto a UE remaining on premises 110 but outside of coverage area 108. Inthis regard, where femto node 106 determines UL RSSI is not steadilydecreasing, femto node 106 can calibrate transmit power to expandcoverage area 108 in an attempt to provide service to UE 112. In anycase, the transmit power of femto node 106 is adjusted to attempt moreoptimal coverage for UEs within premises 110. In one example, femto node106 can calibrate its transmit power to serve UE 112 at fixed incrementsuntil UE 112 is served, at one or more increments determined based onthe RSSI measurements, and/or the like.

Turning to FIG. 2, an example wireless communication system 200 isillustrated that facilitates adjusting power of a femto node. System 200comprises a UE 202 that communicates with a femto node 204 to receiveaccess to a wireless network. In addition, system 200 can include amacro node 206 that can provide access to the wireless network in alarger coverage area. As described, femto node 204 can be a smallercoverage access point, such as a H(e)NB, etc., in a home of a user, anoffice, and/or the like. UE 202, as described, can be a mobile terminal,stationary terminal, modem (or other tethered UE), a portion thereof,and/or the like.

UE 202 optionally comprises a measurement report providing component 208for communicating a measurement report to one or more base stations.

Femto node 204 can include a power calibrating component 212 fordetermining a transmit power calibration for the femto node 204 based atleast in part on one or more determined parameters regarding a UE, and ausage estimating component 214 for observing parameters for determiningUE usage of femto node 204. Usage estimating component 214 canoptionally include one or more components to facilitate observing suchparameters, such as a power adjusting component 216 for adjusting atransmit power of femto node 204, a UE mode determining component 218for determining an operating mode of a UE connected to femto node 204, aUE registration receiving component 220 for obtaining registrationrequests from one or more UEs, a measurement report receiving component222 for obtaining measurement reports from one or more UEs, and/or aRSSI measuring component 224 for obtaining UL RSSI values at femto node204.

According to an example, UE 202 can communicate with femto node 204 toreceive wireless network access. Femto node 204, however, may notadequately cover certain areas within a premises in which the femto node204 resides. Thus UE 202 can handover to macro node 206 when movingoutside of coverage of femto node 204 but still within the premises.Usage estimating component 214 can attempt to detect such usage of thefemto node 204 based on observing one or more parameters, as describedabove and further herein, and power calibrating component 212 candetermine a power calibration for femto node 204 transmissions toaccordingly expand coverage of femto node 204 within the premises.

In one example, UE mode determining component 218 can detect UE 202transitioning from an idle to active communications mode with femto node204 (e.g., where UE 202 receives or initiates a call over femto node204). For instance, this can include receiving a random access preambleor other indication of a communications mode switch from the UE 202,receiving a page for the UE 202 from a core network component, and/orthe like. A UE in an idle communications mode, also referred to hereinas idle mode, can retain resources for receiving paging signals from abase station while terminating other resources with the base station toconserve power with the UE is not using a data link. A UE in an activecommunications mode, also referred to herein as idle mode, is servedover multiple resources to facilitate data link communications.

In this example, power adjusting component 216 can determine to increasetransmit power of a pilot channel at least during the period of timeduring which UE 202 is in active mode, which can result in improvedcommunications of UE 202 at femto node 204 and receiving measurementreports from UE 202 for calibrating a transmit power. In one example,power adjusting component 216 can determine to increase the transmitpower of femto node 204 by a fixed value (e.g., 10 decibel (dB)), adynamic value, a value computed based on historical transmit power,and/or the like, while the UE 202 is in the active communications mode.

For example, power adjusting component 216 can increase transmit powerfor a common pilot indicator channel (CPICH) transmission of femto node204 from a base transmit power to provide an extended coverage area atleast while UE 202 is in active communications mode. This CPICH transmitpower can be referred to as P_CPICH(active, t) for a given time period,t, in example computations described herein. During this time,measurement report receiving component 222 can obtain measurementreports from UE 202. In this example, measurement report providingcomponent 208 generates and provides measurement reports to femto node204 that at least include a signal strength or quality measurement offemto node 204. This can be based on solicitation from femto node 204 orotherwise according to a timer or other event based on communicating inactive mode with femto node 204. It is to be appreciated, for example,that power adjusting component 216 can decrease the transmit power whenUE mode determining component 218 detects a transition of UE 202 back toidle communications mode. This transmit power can be referred to asP(idle). This can include decreasing to the base transmit power and/orto a transmit power computed by power calibrating component 212, asdescribed herein. In addition, it is to be appreciated that femto node204 can modify transmit power of other channels in addition oralternatively to the CPICH transmit power, including power of broadcastchannels, etc. In addition, for example modification of such channelscan be proportional to the modified CPICH transmit power.

In one example, measurement report providing component 208 cancommunicate periodic measurement reports to femto node 204 while inactive mode, where the femto node 204 is using the increased transmitpower. For example, a measurement report can include a list of basestations from which UE 202 can receive signals, along with measurementsof the signal strength or quality performed by UE 202 (e.g., ratio ofenergy per chip to power spectral density (Ec/Io), received signal codepower (RSCP), pathloss, etc., of femto node 204, macro node 206, etc.).In one example, the measurement reports can be substantially similar tothose utilized for evaluating handover for UE 202.

Measurement report receiving component 222 can obtain the measurementreports, and usage estimating component 214 can determine a usagepattern of the UE 202, which includes observing one or more parametersof UE 202 based on the measurement reports. This can include observing aminimum signal strength or quality of a signal from femto node 204 asexperienced at a location by UE 202 during the active mode (e.g., asreceived in one or more measurement reports). In this regard, powercalibrating component 212 can calibrate the base transmit power of femtonode 204 such that the determined minimum signal strength or quality offemto node 204 experienced by the UE 202 at the location does not fallbelow a threshold resulting in handover of UE 202 when femto node 204 isoperating at the base transmit power. The calibrated base transmit powercan correspond to the P(idle), as described above, and thus a coveragearea of femto node 204 is expanded during idle communications mode of UE202 as well to serve the UE 202 in additional areas of the premises.

In one specific example, where the measurement reports include a CPICHRSCP measurement of X dB for macro node 206 and RSCP measurement of Y dBof femto node 204, where power adjusting component 216 increasestransmit power of femto node 204 for determining the power calibration.Then, to calibrate transmit power to avoid handover of UE 202 to themacro node 206 at the UE 202 location, power calibrating component 212can set the base transmit power of femto node 204 asP_current−Y+X+ReportingRange+Hyst, where P_current is the increasedtransmit power, and ReportingRange and Hyst are handover parameters atthe femto node 204.

For example, where the channel conditions reported in the measurementreport are favorable (e.g., signal strength or quality of the femto node204 is a threshold difference greater than that of macro node 206),usage estimating component 214 can determine that a transmit powercalibration can allow UE 202 to experience such channel conditions whencommunicating in idle mode. Power calibrating component 212 cancalibrate the base transmit power of the femto node 204 according to thetransmit power calibration, effectively extending the coverage area offemto node 204. It is to be appreciated that power calibrating component212 can additionally consider a level of possible interference caused tomacro node 206 and/or related UEs communicating therewith whendetermining whether to calibrate the transmit power (e.g., powercalibrating component 212 can modify a computed calibration based on thedetermined level of interference, cancel the power calibration based ondetermined interference, and/or the like).

In one example, in increasing the transmit power for detecting usage bythe UE 202 described above, power adjusting component 216 can determinea power adjustment for the UE 202 in an active communications mode as afixed adjustment based on constant c1, which can be hardcoded,configured, or otherwise received from a wireless network, as described(e.g., 10 dB):

P_CPICH(active, t)=P(idle)+c1

In another example, power adjusting component 216 can determine a poweradjustment based at least in part on the measurement reports receivedfrom UE 202. For example, power adjusting component 216 can calculate atransmit power adjustment based at least in part on adding a reportedsignal strength of a strongest macro node (e.g., macro node 206), asreceived in the measurement reports, to a determined pathloss edgemeasurement at which femto node 204 initiates handout of UE 202 to themacro node:

P_CPICH(active, t)=RSCP_strongest_macro(t−t1)+PL_handout_edge+c2

where RSCP_strongest_macro is the pilot signal strength at a macro node206 received in one or more measurement reports from UE 202,PL_handout_edge is the pathloss edge at which handout to macro node 206occurs, and c2 is a constant. For example, power adjusting component 216determines the pathloss edge measurement based on a current or idle modetransmit power of the femto node 204, based on one or more parametersreceived from the UE 202, based on a value received over a wirelessnetwork, and/or the like. In another example, power adjusting component216 can use the following formula to determine a transmit poweradjustment for a UE in active mode:

P_CPICH(active, t)=P_CPICH(active,t)+max(RSCP_strongest_macro(t−t1)+c3−RSCP _femto,0)

where RSCP_femto is a pilot signal strength of femto node 204 receivedin one or more measurement reports from UE 202, and c3 is a constant.

In yet another example, power adjusting component 216 can determine atransmit power adjustment based on historical measurement reports fromUE 202 in a previous switch to active mode. For example, power adjustingcomponent 216 can compute the transmit power adjustment based on apercentile of measurements (e.g., signal strength or quality) ofstrongest macro nodes received over a period of time (e.g., for thegiven day). Power adjusting component 216 can add this computed value tothe pathloss edge measurement and/or a constant described above:

P_CPICH(active, t)=percentileRSCP_strongest_macro+PL_handout_edge+c2

where the percentile is an xth percentile (e.g., x=95 or some othervalue) over a period of time (e.g., in a given day). In any case, poweradjusting component 216 can set the transmit power for CPICH based onone or more of the above. Regardless of the mechanism used, during theperiod of CPICH power increase described above, usage estimatingcomponent 214 can determine usage of the UE 202 at femto node 204 basedon one or more parameters, such as received measurement reports, forcalibrating overall transmit power of the femto node 204.

In another example, usage estimating component 214 can estimate UE usageof femto node 204 based at least in part on observing idle moderegistrations received from UE 202, and/or other UEs, at femto node 204.In this example, power adjusting component 216 can effectuate a periodictransmit power burst (e.g., for CPICH transmissions) for a shortduration of time at femto node 204 to extend the coverage area. Thetransmit power burst can relate to increasing transmit power of thefemto node 204 pilot channel from a base transmit power for the shortduration of time, and the transmit power burst can be at a large powerto facilitate receiving measurement reports from various neighboringUEs. For example, the duration of time can be similar to a minimum timebetween evaluating neighboring base stations for handover at a UE (e.g.,on the order of minutes) so as not to cause substantial interference tomacro node 206 or other nodes or UEs for an extended period of time.Moreover, in an example, power adjusting component 216 can periodicallyadjust the transmit power during times when member UEs are expected tobe within coverage of femto node 204 and/or during times of low networkactivity (e.g., early morning hours) so as not to cause substantialinterference to macro node 206 during a period of heavy use. Also, forexample, power adjusting component 216 can continue with periodicallyadjusting the transmit power for the pilot channel over a period of time(e.g., days) until sufficient measurement reports are gathered tocalibrate the base transmit power, until one or more member UEs areserved by the femto node 204, and/or the like.

In one example, power adjusting component 216 can increase a transmitpower for CPICH by a value, increase the transmit power as necessary tocapture UEs having a certain pathloss (e.g., 90 db), and/or the like.During the duration of time for the extended coverage area, UEregistration receiving component 220 may obtain one or more additionalUE registration attempts from UEs reselecting in idle mode from adifferent base station (e.g., macro node 206). In one example, theregistration attempts can include measurement reports or at least asignal strength or quality measurement (e.g., Ec/Io, RSCP, pathloss,etc.) of femto node 204 and/or one or more macro nodes, such as macronode 206, at the UE.

For example, as described, femto node 204 can utilize restrictedassociation to communicate with UE 202 while restricting access of otherUEs. For instance, femto node 204 can implement a closed or hybridcommunications mode associated with a closed subscriber group (CSG). Forexample, femto node 204 can broadcast CSG support and access mode suchthat UEs receiving the broadcast can determine whether to access femtonode 204. In this example, UEs in the expanded coverage areatransmitting measurement reports to the femto node 204 can indicate tothe femto node whether access to the CSG is allowed. In another example,UE registration receiving component 220 and/or measurement reportreceiving component 222 can determine whether one or more UEs are memberUEs allowed to access femto node 204 based on receiving an identifierthereof in the registration attempt or measurement report, and obtainingsubscription information from the wireless network based on theidentifier.

In this example, usage estimating component 214 can utilize themeasurement reports to determine UE usage of femto node 204; themeasurement reports are received over a few days, for example, andobserved to determine a pathloss of the UE 202 to femto node 204. Forexample, calibrating transmit power based on the determined pathloss canallow for covering previous idle resting locations for which femto node204 coverage is desired but not available. For instance, usageestimating component 214 can detect one or more UEs that are a member ofthe CSG of femto node 204 registering during the transmit power burstfor the pilot channel, such as UE 202. Usage estimating component 214can utilize such registrations and/or corresponding measurement reportsto compute a transmit power calibration for femto node 204. For example,power calibrating component 212 can accordingly calibrate the transmitpower for femto node 204 after the transmit power burst to cover the oneor more member UEs, such as UE 202. Moreover, as described, powercalibrating component 212 can consider potential interference tonon-member UEs in determining a transmit power calibration. For example,power calibrating component 212 can evaluate measurement reportsreceived from non-member UEs to ensure a selected transmit powercalibration does not substantially interfere with the non-member UEs.

For example, usage estimating component 214 can determine a transmitpower calibration necessary to accommodate a member UE, such as UE 202,that favors macro node 206 when femto node 204 operates at a currentbase transmit power (e.g., according to a received measured signalstrength of macro node 206). Power calibrating component 212 can thendetermine if the power calibration would cause interference to one ormore non-member UEs based on their reported measurements of macro node206. For example, power calibrating component 212 can determine a powercalibration to accomplish both ends. Power calibrating component 212 canmodify the transmit power of femto node 204 according to the determinedpower calibration. Moreover, in an example, femto node 204 can estimatea location of UE 202 based on received signal measurements of femto node204, macro node 206, and/or other nodes received in measurement reports(e.g., using triangulation with known location of the nodes).

In another example, usage estimating component 214 can estimate UE 202usage of femto node 204 based at least in part on a UL RSSI at femtonode 204. In this example, usage estimating component 214 can inferwhether UE 202 is within an area that should be covered by femto node204 based at least in part on comparing UL RSSI following handover ofthe UE 202 to another base station over a period of time. For example,UE mode determining component 218 can detect handover (e.g., active modehandout, idle mode reselection, etc.) of a served UE, such as UE 202, toanother base station, such as macro node 206. In this example, RSSImeasuring component 224 can begin measuring uplink RSSI followinghandout or reselection, which can include capturing and processing logsof the interference levels upon handover.

For example, RSSI measuring component 224 can take measurements for aninitial time period upon detecting the handout/reselection, and at leastone subsequent time period following handout/reselection. Themeasurements can include obtaining an averaging of one or more samplesover the time periods, a filtered value representing the one or moresamples, and/or the like. For example, the subsequent time period can bedetermined as a fixed point in time following the initial time period,determined based on one or more detected events, and/or the like. Usageestimating component 214 can compare the measurements to determine ausage of femto node 204 or related parameters for observation todetermine the usage, and/or whether to perform a transmit powercalibration to serve UE 202.

For example, where the UL RSSIs measured over the time periods aresimilar (e.g., within a threshold difference), usage estimatingcomponent 214 can infer that the UE has been within an area intended tobe covered by femto node 204 since handover to macro node 206, and canthus determine to calibrate transmit power to serve UE 202. This can beeffectuated by fixed increment increases of the base transmit poweruntil UE 202 is served, by a calibration determined based on the RSSI,etc. In another example, where the later measured RSSIs are over athreshold difference lower than the initial measured RSSIs (and/orcontinue to decrease over time), usage estimating component 214 caninfer that UE 202 is not in an area intended to be covered by femto node204, and can thus maintain a current transmit power, decrease transmitpower, etc., allowing UE 202 to continue communicating in macro nodecoverage. Power calibrating component 212 can calibrate transmit poweras determined by usage estimating component 214.

FIGS. 3 and 4 illustrate example UE usage maps at a femto node andassociated RSSI measurements at the femto node. In FIG. 3, an exampleusage map 300 is illustrated with a femto node 302 providing coveragearea 304 over premises 306. In addition, a usage path 308 of a UE isshown where the UE initiates connection to femto node 302 withincoverage area 304 and moves outside of coverage area 304 while still inpremises 306, resulting in handover to a macro node (not shown). Suchusage can be detected, as described, based in part on analyzing UL RSSI.UL RSSI over time at the femto node 302 relating to the UE usage map 300is shown at 310. The UE is handed over to the macro node after exitingcoverage area 304 at 314. UL RSSI can be evaluated over an initial timeperiod 316 beginning at or soon after handover, as well as over asubsequent time period 318, which can be defined as a fixed time periodafter the initial time period 316, defined based on one or more eventsencountered during initial time period 316, and/or the like. As shown,the UL RSSI over time periods 316 and 318 are similar, which canindicate the UE is within the premises 306 in an area intended to becovered by femto node 302, as opposed to where the RSSI in time period318 is at least a threshold lower than RSSI in time period 316. Forexample, measuring the RSSI can include measuring an average or filteredvalue of the RSSI over the time periods 416 and 418.

In FIG. 4, an example usage map 400 is illustrated with a femto node 402providing coverage area 404 over the entire premises 406. In addition, ausage path 408 of a UE is shown where the UE initiates connection withfemto node 402 within coverage area 404 and moves outside of premises406 and coverage area 404, resulting in handover to a macro node (notshown). The UE moving to an area outside of premises 406 can be detectedbased in part on analyzing UL RSSI. For example, UL RSSI over timerelating to the UE usage map 400 is shown at 410. The UE is handed overto the macro node after exiting coverage area 404 at 414. UL RSSI can beevaluated over an initial time period 416 beginning at or soon afterhandover, as well as over a subsequent time period 418, which can bedefined as a fixed time period after the initial time period 416,defined based on one or more events encountered during initial timeperiod 416, and/or the like. As shown, the UL RSSI over time period 418is lower than that over time period 416, which can indicate the UE movesoutside the coverage area 404, as opposed to where the RSSI in timeperiods 416 and 418 is similar and the UE is in an area intended to becovered by femto node 402. In an example, UL RSSI over time periods 418and 416 can be compared to determine the difference is at least at athreshold, as described previously in detecting that UE is movingoutside of coverage area 404. For example, this can include measuring anaverage or filtered value of the RSSI over the time periods 416 and 418.

FIGS. 5-7 illustrate example methodologies relating to expandingcoverage area of a femto node to serve one or more intended UEs. While,for purposes of simplicity of explanation, the methodologies are shownand described as a series of acts, it is to be understood andappreciated that the methodologies are not limited by the order of acts,as some acts may, in accordance with one or more embodiments, occurconcurrently with other acts and/or in different orders from that shownand described herein. For example, it is to be appreciated that amethodology could alternatively be represented as a series ofinterrelated states or events, such as in a state diagram. Moreover, notall illustrated acts may be required to implement a methodology inaccordance with one or more embodiments.

FIG. 5 depicts an example methodology 500 for calibrating power of afemto node to serve one or more intended UEs.

At 502, a transmit power of a femto node can be increased from a basetransmit power for a duration of time. In one example, the transmitpower can be increased based on detecting a UE switch from an idlecommunications mode to an active communications mode, where the increasein transmit power can last for the duration of active communicationsmode at the UE. In this example, the transmit power can be increased bya fixed value, by a dynamic value computed based on one or moremeasurement reports (including at least a measurement of the femto nodeand/or of a strongest macro node in the vicinity of the one or more UEs)received from one or more UEs, a value computed based on historicalmeasurement reports (including at least a measurement of the femto nodeand/or of a strongest macro node in the vicinity of the one or more UEs)received from one or more UEs, and/or the like.

In another example, the transmit power is periodically increased over ashort period of time (a burst) for a duration of time sufficient tocapture registration requests from UEs in the vicinity. For example,this can be on the order of minutes and/or can correlate to a time at aUE for evaluating cells for reselection. In addition, the burst canoccur in a period of time where interference to surrounding nodes isexpected to be minimized and/or when member UEs are expected to be inthe vicinity of the femto node (e.g., during late night or early morninghours). Moreover, periodic increasing of the transmit power can ceaseonce one or more member UEs are served by the femto node.

At 504, one or more measurement reports can be received from one or moreUEs during the duration of time. For example, this can be a result ofthe increase in transmit power. Measurement reports can be received fromserved UEs (e.g., a UE switching to an active mode), non-member UEs thatmay be interfered by the femto node during the duration of time, and/orthe like. In addition, as described, the measurement reports can bereceived within or in connection with one or more registration attemptsfrom the UEs.

At 506, the base transmit power of the femto node can be calibratedbased in part on the one or more measurement reports and the increasedtransmit power. Thus, for example, a power calibration can be determinedto allow for serving one or more member UEs from which measurementreports are received, while mitigating interference to one or morenon-member UEs from which measurement reports are received. For example,a transmit power to serve the member UEs can be determined based on theincreased transmit power and the corresponding pathloss reported by theUE, and similarly, the transmit power to mitigate interference to one ormore non-member UEs can be determined based on the increased transmitpower and corresponding measurement reports received from the non-memberUEs. As described, the member and non-member UEs can be identified basedon an identifier in the measurement report or registration requests fromthe UEs, subscription information obtained from the wireless network, anindication from the UE of whether the UE can access a CSG of the femtonode, and/or the like.

FIG. 6 illustrates an example methodology 600 for calibrating transmitpower of a femto node.

At 602, a handover of a served UE from a femto node to another node canbe detected. This can be detected at the femto node based on the femtonode causing or otherwise being instructed to perform the handover.

At 604, an uplink RSSI can be measured at the femto node over aplurality of time periods based on the handover. This can includemeasuring over an initial time period following handover and asubsequent time period. The time periods can be defined as fixed timesfollowing handover, by one or more events occurring at the femto node,and/or the like, as described. The uplink RSSIs can be measured fromlogs at the femto node, and can include measuring an average or filteredvalue over the time periods.

At 606, a transmit power of the femto node can be calibrated based oncomparing the uplink RSSI measured over the plurality of time periods.For example, this can include determining whether the RSSI over the timeperiods are within a threshold difference of one another. If so, thiscan indicate that a transmit power should be calibrated to include theserved UE that was handed over. As described, such behavior in RSSI canindicate the served UE remained near the femto node despite being handedover to the other node. In this example, the transmit power iscalibrated by increasing the transmit power according to a fixed value,according to a value computed based on a measurement report from theserved UE, and/or the like.

FIG. 7 illustrates an example methodology 700 for increasing transmitpower of a femto node to expand a coverage area thereof.

At 702, a served UE is detected to transition from an idle to an activecommunications mode. For example, this can include receiving a randomaccess request or other indication of a communications mode switch fromthe UE, receiving a page for the UE from a wireless network component,and/or the like.

At 704, a transmit power can be increased for transmitting signals tothe UE. This can improve coverage for the UE at the femto node, whichcan improve communications thereof and/or a user experience at the UE.In addition, as described, receiving measurement reports from the UEduring the active communications mode can facilitate calibrating a basetransmit power of the femto node. In one example, the transmit power canbe decreased to a base transmit power following the UE transitioningfrom the active communications mode to the idle communications mode.

It will be appreciated that, in accordance with one or more aspectsdescribed herein, inferences can be made regarding determining atransmit power calibration for the femto node based on one or morereceived measurement reports, determining a communications mode switchof a UE, determining a transmit power adjustment for a UE switching toan active communications mode, and/or the like, as described. As usedherein, the term to “infer” or “inference” refers generally to theprocess of reasoning about or inferring states of the system,environment, and/or user from a set of observations as captured viaevents and/or data. Inference can be employed to identify a specificcontext or action, or can generate a probability distribution overstates, for example. The inference can be probabilistic—that is, thecomputation of a probability distribution over states of interest basedon a consideration of data and events. Inference can also refer totechniques employed for composing higher-level events from a set ofevents and/or data. Such inference results in the construction of newevents or actions from a set of observed events and/or stored eventdata, whether or not the events are correlated in close temporalproximity, and whether the events and data come from one or severalevent and data sources.

FIG. 8 is an illustration of a system 800 that facilitates calibratingtransmit power of a femto node. System 800 includes a eNB 802 having areceiver 810 that receives signal(s) from one or more mobile devices oreNBs 804 through a plurality of receive antennas 806 (e.g., which can beof multiple network technologies), and a transmitter 842 that transmitsto the one or more mobile devices or eNBs 804 through a plurality oftransmit antennas 808 (e.g., which can be of multiple networktechnologies). For example, eNB 802 can transmit signals received fromeNBs 804 to other eNBs 804, and/or vice versa. Receiver 810 can receiveinformation from one or more receive antennas 806 and is operativelyassociated with a demodulator 812 that demodulates received information.In addition, in an example, receiver 810 can receive from a wiredbackhaul link. Though depicted as separate antennas, it is to beappreciated that at least one of receive antennas 806 and acorresponding one of transmit antennas 808 can be combined as the sameantenna. Demodulated symbols are analyzed by a processor 814, which iscoupled to a memory 816 that stores information related to performingone or more aspects described herein.

Processor 814, for example, can be a processor dedicated to analyzinginformation received by receiver 810 and/or generating information fortransmission by a transmitter 842, a processor that controls one or morecomponents of eNB 802, and/or a processor that analyzes informationreceived by receiver 810, generates information for transmission bytransmitter 842, and controls one or more components of eNB 802. Inaddition, processor 814 can perform one or more functions describedherein and/or can communicate with components for such a purpose.

Memory 816, as described, is operatively coupled to processor 814 andcan store data to be transmitted, received data, information related toavailable channels, data associated with analyzed signal and/orinterference strength, information related to an assigned channel,power, rate, or the like, and any other suitable information forestimating a channel and communicating via the channel. Memory 816 canadditionally store protocols and/or algorithms associated withcalibrating transmit power of eNB 802.

It will be appreciated that the data store (e.g., memory 816) describedherein can be either volatile memory or nonvolatile memory, or caninclude both volatile and nonvolatile memory. By way of illustration,and not limitation, nonvolatile memory can include read only memory(ROM), programmable ROM (PROM), electrically programmable ROM (EPROM),electrically erasable PROM (EEPROM), or flash memory. Volatile memorycan include random access memory (RAM), which acts as external cachememory. By way of illustration and not limitation, RAM is available inmany forms such as synchronous RAM (SRAM), dynamic RAM (DRAM),synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhancedSDRAM (ESDRAM), Synchlink DRAM (SLDRAM), and direct Rambus RAM (DRRAM).The memory 816 of the subject systems and methods is intended tocomprise, without being limited to, these and any other suitable typesof memory.

Processor 814 is further optionally coupled to a power calibratingcomponent 818, which can be similar to power calibrating component 212,and/or usage estimating component 820, which can be similar to usageestimating component 214, and can comprise one or more furthercomponents thereof. Moreover, for example, processor 814 can modulatesignals to be transmitted using modulator 840, and transmit modulatedsignals using transmitter 842. Transmitter 842 can transmit signals tomobile devices or eNBs 804 over Tx antennas 808. Furthermore, althoughdepicted as being separate from the processor 814, it is to beappreciated that the power calibrating component 818, usage estimatingcomponent 820, demodulator 812, and/or modulator 840 can be part of theprocessor 814 or multiple processors (not shown), and/or stored asinstructions in memory 816 for execution by processor 814.

FIG. 9 illustrates a system 900 for calibrating power of a femto node.For example, system 900 can reside at least partially within a femtonode or other low power base station. It is to be appreciated thatsystem 900 is represented as including functional blocks, which can befunctional blocks that represent functions implemented by a processor,software, or combination thereof (e.g., firmware). System 900 includes alogical grouping 902 of electrical components that can act inconjunction. For instance, logical grouping 902 can include anelectrical component for increasing a transmit power of a femto nodefrom a base transmit power for a duration of time 904. As described,this can be based on a detected communications mode switch, and/or cancorrespond to a short power burst to receiving registration attemptsfrom one or more UEs. Further, logical grouping 902 can include anelectrical component for receiving one or more measurement reports fromone or more UEs during the duration of time 906.

As described, the measurement reports can include signal strength orquality measurements of the femto node and/or one or more other nodes,and/or can be received in conjunction with registration requests fromthe one or more UEs. Logical grouping 902 can further include anelectrical component for calibrating the base transmit power of thefemto node based in part on the one or more measurement reports and theincreased transmit power 908. Moreover, in an example, the transmitpower can be increased by electrical component 904 based on themeasurement reports or a history of measurement reports (or a fixedvalue), as described.

For example, electrical component 904 can include a power adjustingcomponent 216, as described above. In addition, for example, electricalcomponent 906, in an aspect, can include a measurement report receivingcomponent 222, and/or electrical component 908 can include a powercalibrating component 212, a usage estimating component 214, and/or thelike, as described.

Additionally, system 900 can include a memory 910 that retainsinstructions for executing functions associated with the electricalcomponents 904, 906, and 908. While shown as being external to memory910, it is to be understood that one or more of the electricalcomponents 904, 906, and 908 can exist within memory 910. Moreover, forexample, electrical components 904, 906, and 908 can be interconnectedby a bus 912. In one example, electrical components 904, 906, and 908can include at least one processor, or each electrical component 904,906, and 908 can be a corresponding module of at least one processor.Moreover, in an additional or alternative example, electrical components904, 906, and 908 can be a computer program product comprising acomputer readable medium, where each electrical component 904, 906, and908 can be corresponding code.

FIG. 10 illustrates a system 1000 for calibrating transmit power of afemto node. For example, system 1000 can reside at least partiallywithin a femto node or other low power base station. It is to beappreciated that system 1000 is represented as including functionalblocks, which can be functional blocks that represent functionsimplemented by a processor, software, or combination thereof (e.g.,firmware). System 1000 includes a logical grouping 1002 of electricalcomponents that can act in conjunction. For instance, logical grouping1002 can include an electrical component for detecting a handover of aserved UE from a femto node to another node 1004. Further, logicalgrouping 1002 can include an electrical component for measuring anuplink RSSI at the femto node over a plurality of time periods based onthe detecting the handover 1006.

Logical grouping 1002 can further include an electrical component forcalibrating a transmit power of the femto node based on comparing theuplink RSSI measured over the plurality of time periods 1008. Asdescribed, this can include determining whether the RSSI measurementsare within a threshold difference, which can indicate to increase a basetransmit power at the femto node, for example.

In an example, electrical component 1004 can include a UE modedetermining component 218, as described above. In addition, for example,electrical component 1006, in an aspect, can include a RSSI measuringcomponent 224, and/or electrical component 1008 can include a powercalibrating component 212, usage estimating component 214, and/or thelike, as described.

Additionally, system 1000 can include a memory 1010 that retainsinstructions for executing functions associated with the electricalcomponents 1004, 1006, and 1008. While shown as being external to memory1010, it is to be understood that one or more of the electricalcomponents 1004, 1006, and 1008 can exist within memory 1010. Moreover,for example, electrical components 1004, 1006, and 1008 can beinterconnected by a bus 1012. In one example, electrical components1004, 1006, and 1008 can include at least one processor, or eachelectrical component 1004, 1006, and 1008 can be a corresponding moduleof at least one processor. Moreover, in an additional or alternativeexample, electrical components 1004, 1006, and 1008 can be a computerprogram product comprising a computer readable medium, where eachelectrical component 1004, 1006, and 1008 can be corresponding code.

FIG. 11 illustrates a wireless communication system 1100 in accordancewith various embodiments presented herein. System 1100 comprises a basestation 1102 that can include multiple antenna groups. For example, oneantenna group can include antennas 1104 and 1106, another group cancomprise antennas 1108 and 1110, and an additional group can includeantennas 1112 and 1114. Two antennas are illustrated for each antennagroup; however, more or fewer antennas can be utilized for each group.Base station 1102 can additionally include a transmitter chain and areceiver chain, each of which can in turn comprise a plurality ofcomponents or modules associated with signal transmission and reception(e.g., processors, modulators, multiplexers, demodulators,demultiplexers, antennas, etc.), as is appreciated.

Base station 1102 can communicate with one or more mobile devices suchas mobile device 1116 and mobile device 1122; however, it is to beappreciated that base station 1102 can communicate with substantiallyany number of mobile devices similar to mobile devices 1116 and 1122.Mobile devices 1116 and 1122 can be, for example, cellular phones, smartphones, laptops, handheld communication devices, handheld computingdevices, satellite radios, global positioning systems, PDAs, and/or anyother suitable device for communicating over wireless communicationsystem 1100. As depicted, mobile device 1116 is in communication withantennas 1112 and 1114, where antennas 1112 and 1114 transmitinformation to mobile device 1116 over a forward link 1118 and receiveinformation from mobile device 1116 over a reverse link 1120. Moreover,mobile device 1122 is in communication with antennas 1104 and 1106,where antennas 1104 and 1106 transmit information to mobile device 1122over a forward link 1124 and receive information from mobile device 1122over a reverse link 1126. In a frequency division duplex (FDD) system,forward link 1118 can utilize a different frequency band than that usedby reverse link 1120, and forward link 1124 can employ a differentfrequency band than that employed by reverse link 1126, for example.Further, in a time division duplex (TDD) system, forward link 1118 andreverse link 1120 can utilize a common frequency band and forward link1124 and reverse link 1126 can utilize a common frequency band.

Each group of antennas and/or the area in which they are designated tocommunicate can be referred to as a sector of base station 1102. Forexample, antenna groups can be designed to communicate to mobile devicesin a sector of the areas covered by base station 1102. In communicationover forward links 1118 and 1124, the transmitting antennas of basestation 1102 can utilize beamforming to improve signal-to-noise ratio offorward links 1118 and 1124 for mobile devices 1116 and 1122. Also,while base station 1102 utilizes beamforming to transmit to mobiledevices 1116 and 1122 scattered randomly through an associated coverage,mobile devices in neighboring cells can be subject to less interferenceas compared to a base station transmitting through a single antenna toall its mobile devices. Moreover, mobile devices 1116 and 1122 cancommunicate directly with one another using a peer-to-peer or ad hoctechnology as depicted.

FIG. 12 shows an example wireless communication system 1200. Thewireless communication system 1200 depicts one base station 1210 and onemobile device 1250 for sake of brevity. However, it is to be appreciatedthat system 1200 can include more than one base station and/or more thanone mobile device, wherein additional base stations and/or mobiledevices can be substantially similar or different from example basestation 1210 and mobile device 1250 described below. Moreover, basestation 1210 can be a low power base station, in one example, such asone or more femto nodes previously described. In addition, it is to beappreciated that base station 1210 and/or mobile device 1250 can employthe example systems (FIGS. 1, 2, and 8-11), usage maps (FIGS. 3 and 4),and/or methods (FIGS. 5-7) described herein to facilitate wirelesscommunication there between. For example, components or functions of thesystems and/or methods described herein can be part of a memory 1232and/or 1272 or processors 1230 and/or 1270 described below, and/or canbe executed by processors 1230 and/or 1270 to perform the disclosedfunctions.

At base station 1210, traffic data for a number of data streams isprovided from a data source 1212 to a transmit (TX) data processor 1214.According to an example, each data stream can be transmitted over arespective antenna. TX data processor 1214 formats, codes, andinterleaves the traffic data stream based on a particular coding schemeselected for that data stream to provide coded data.

The coded data for each data stream can be multiplexed with pilot datausing orthogonal frequency division multiplexing (OFDM) techniques.Additionally or alternatively, the pilot symbols can be frequencydivision multiplexed (FDM), time division multiplexed (TDM), or codedivision multiplexed (CDM). The pilot data is typically a known datapattern that is processed in a known manner and can be used at mobiledevice 1250 to estimate channel response. The multiplexed pilot andcoded data for each data stream can be modulated (e.g., symbol mapped)based on a particular modulation scheme (e.g., binary phase-shift keying(BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying(M-PSK), M-quadrature amplitude modulation (M-QAM), etc.) selected forthat data stream to provide modulation symbols. The data rate, coding,and modulation for each data stream can be determined by instructionsperformed or provided by processor 1230.

The modulation symbols for the data streams can be provided to a TX MIMOprocessor 1220, which can further process the modulation symbols (e.g.,for OFDM). TX MIMO processor 1220 then provides N_(T) modulation symbolstreams to N_(T) transmitters (TMTR) 1222 a through 1222 t. In variousembodiments, TX MIMO processor 1220 applies beamforming weights to thesymbols of the data streams and to the antenna from which the symbol isbeing transmitted.

Each transmitter 1222 receives and processes a respective symbol streamto provide one or more analog signals, and further conditions (e.g.,amplifies, filters, and upconverts) the analog signals to provide amodulated signal suitable for transmission over the MIMO channel.Further, N_(T) modulated signals from transmitters 1222 a through 1222 tare transmitted from N_(T) antennas 1224 a through 1224 t, respectively.

At mobile device 1250, the transmitted modulated signals are received byN_(R) antennas 1252 a through 1252 r and the received signal from eachantenna 1252 is provided to a respective receiver (RCVR) 1254 a through1254 r. Each receiver 1254 conditions (e.g., filters, amplifies, anddownconverts) a respective signal, digitizes the conditioned signal toprovide samples, and further processes the samples to provide acorresponding “received” symbol stream.

An RX data processor 1260 can receive and process the N_(R) receivedsymbol streams from N_(R) receivers 1254 based on a particular receiverprocessing technique to provide N_(T) “detected” symbol streams. RX dataprocessor 1260 can demodulate, deinterleave, and decode each detectedsymbol stream to recover the traffic data for the data stream. Theprocessing by RX data processor 1260 is complementary to that performedby TX MIMO processor 1220 and TX data processor 1214 at base station1210.

The reverse link message can comprise various types of informationregarding the communication link and/or the received data stream. Thereverse link message can be processed by a TX data processor 1238, whichalso receives traffic data for a number of data streams from a datasource 1236, modulated by a modulator 1280, conditioned by transmitters1254 a through 1254 r, and transmitted back to base station 1210.

At base station 1210, the modulated signals from mobile device 1250 arereceived by antennas 1224, conditioned by receivers 1222, demodulated bya demodulator 1240, and processed by a RX data processor 1242 to extractthe reverse link message transmitted by mobile device 1250. Further,processor 1230 can process the extracted message to determine whichprecoding matrix to use for determining the beamforming weights.

Processors 1230 and 1270 can direct (e.g., control, coordinate, manage,etc.) operation at base station 1210 and mobile device 1250,respectively. Respective processors 1230 and 1270 can be associated withmemory 1232 and 1272 that store program codes and data. For example,processor 1230 and/or 1270 can execute, and/or memory 1232 and/or 1272can store instructions related to functions and/or components describedherein, such as calibrating transmit power of a femto node (e.g., basedon temporarily increasing the transmit power, measuring UL RSSIfollowing handover, etc.), as described.

FIG. 13 illustrates a wireless communication system 1300, configured tosupport a number of users, in which the teachings herein may beimplemented. The system 1300 provides communication for multiple cells1302, such as, for example, macro cells 1302A-1302G, with each cellbeing serviced by a corresponding access node 1304 (e.g., access nodes1304A-1304G). As shown in FIG. 13, access terminals 1306 (e.g., accessterminals 1306A-1306L) can be dispersed at various locations throughoutthe system over time. Each access terminal 1306 can communicate with oneor more access nodes 1304 on a forward link (FL) and/or a reverse link(RL) at a given moment, depending upon whether the access terminal 1306is active and whether it is in soft handoff, for example. The wirelesscommunication system 1300 can provide service over a large geographicregion.

FIG. 14 illustrates an exemplary communication system 1400 where one ormore femto nodes are deployed within a network environment.Specifically, the system 1400 includes multiple femto nodes 1410A and1410B (e.g., femtocell nodes or H(e)NB) installed in a relatively smallscale network environment (e.g., in one or more user residences 1430).Each femto node 1410 can be coupled to a wide area network 1440 (e.g.,the Internet) and a mobile operator core network 1450 via a digitalsubscriber line (DSL) router, a cable modem, a wireless link, or otherconnectivity means (not shown). As will be discussed below, each femtonode 1410 can be configured to serve associated access terminals 1420(e.g., access terminal 1420A) and, optionally, alien access terminals1420 (e.g., access terminal 1420B). In other words, access to femtonodes 1410 can be restricted such that a given access terminal 1420 canbe served by a set of designated (e.g., home) femto node(s) 1410 but maynot be served by any non-designated femto nodes 1410 (e.g., a neighbor'sfemto node).

FIG. 15 illustrates an example of a coverage map 1500 where severaltracking areas 1502 (or routing areas or location areas) are defined,each of which includes several macro coverage areas 1504. Here, areas ofcoverage associated with tracking areas 1502A, 1502B, and 1502C aredelineated by the wide lines and the macro coverage areas 1504 arerepresented by the hexagons. The tracking areas 1502 also include femtocoverage areas 1506. In this example, each of the femto coverage areas1506 (e.g., femto coverage area 1506C) is depicted within a macrocoverage area 1504 (e.g., macro coverage area 1504B). It should beappreciated, however, that a femto coverage area 1506 may not lieentirely within a macro coverage area 1504. In practice, a large numberof femto coverage areas 1506 can be defined with a given tracking area1502 or macro coverage area 1504. Also, one or more pico coverage areas(not shown) can be defined within a given tracking area 1502 or macrocoverage area 1504.

Referring again to FIG. 14, the owner of a femto node 1410 can subscribeto mobile service, such as, for example, 3G mobile service, offeredthrough the mobile operator core network 1450. In addition, an accessterminal 1420 can be capable of operating both in macro environments andin smaller scale (e.g., residential) network environments. Thus, forexample, depending on the current location of the access terminal 1420,the access terminal 1420 can be served by an access node 1460 or by anyone of a set of femto nodes 1410 (e.g., the femto nodes 1410A and 1410Bthat reside within a corresponding user residence 1430). For example,when a subscriber is outside his home, he is served by a standard macrocell access node (e.g., node 1460) and when the subscriber is at home,he is served by a femto node (e.g., node 1410A). Here, it should beappreciated that a femto node 1410 can be backward compatible withexisting access terminals 1420.

A femto node 1410 can be deployed on a single frequency or, in thealternative, on multiple frequencies. Depending on the particularconfiguration, the single frequency or one or more of the multiplefrequencies can overlap with one or more frequencies used by a macrocell access node (e.g., node 1460). In some aspects, an access terminal1420 can be configured to connect to a preferred femto node (e.g., thehome femto node of the access terminal 1420) whenever such connectivityis possible. For example, whenever the access terminal 1420 is withinthe user's residence 1430, it can communicate with the home femto node1410.

In some aspects, if the access terminal 1420 operates within the mobileoperator core network 1450 but is not residing on its most preferrednetwork (e.g., as defined in a preferred roaming list), the accessterminal 1420 can continue to search for the most preferred network(e.g., femto node 1410) using a Better System Reselection (BSR), whichcan involve a periodic scanning of available systems to determinewhether better systems are currently available, and subsequent effortsto associate with such preferred systems. Using an acquisition tableentry (e.g., in a preferred roaming list), in one example, the accessterminal 1420 can limit the search for specific band and channel. Forexample, the search for the most preferred system can be repeatedperiodically. Upon discovery of a preferred femto node, such as femtonode 1410, the access terminal 1420 selects the femto node 1410 forcamping within its coverage area.

A femto node can be restricted in some aspects. For example, a givenfemto node can only provide certain services to certain accessterminals. In deployments with so-called restricted (or closed)association, a given access terminal can only be served by the macrocell mobile network and a defined set of femto nodes (e.g., the femtonodes 1410 that reside within the corresponding user residence 1430). Insome implementations, a femto node can be restricted to not provide, forat least one access terminal, at least one of: signaling, data access,registration, paging, or service.

In some aspects, a restricted femto node (which can also be referred toas a Closed Subscriber Group H(e)NB) is one that provides service to arestricted provisioned set of access terminals. This set can betemporarily or permanently extended as necessary. In some aspects, aClosed Subscriber Group (CSG) can be defined as the set of access nodes(e.g., femto nodes) that share a common access control list of accessterminals. A channel on which all femto nodes (or all restricted femtonodes) in a region operate can be referred to as a femto channel.

Various relationships can thus exist between a given femto node and agiven access terminal. For example, from the perspective of an accessterminal, an open femto node can refer to a femto node with norestricted association. A restricted femto node can refer to a femtonode that is restricted in some manner (e.g., restricted for associationand/or registration). A home femto node can refer to a femto node onwhich the access terminal is authorized to access and operate on. Aguest femto node can refer to a femto node on which an access terminalis temporarily authorized to access or operate on. An alien femto nodecan refer to a femto node on which the access terminal is not authorizedto access or operate on (e.g., the access terminal is a non-member),except for perhaps emergency situations (e.g., 911 calls).

From a restricted femto node perspective, a home access terminal canrefer to an access terminal that authorized to access the restrictedfemto node. A guest access terminal can refer to an access terminal withtemporary access to the restricted femto node. An alien access terminalcan refer to an access terminal that does not have permission to accessthe restricted femto node, except for perhaps emergency situations, forexample, 911 calls (e.g., an access terminal that does not have thecredentials or permission to register with the restricted femto node).

For convenience, the disclosure herein describes various functionalityin the context of a femto node. It should be appreciated, however, thata pico node can provide the same or similar functionality as a femtonode, but for a larger coverage area. For example, a pico node can berestricted, a home pico node can be defined for a given access terminal,and so on.

A wireless multiple-access communication system can simultaneouslysupport communication for multiple wireless access terminals. Asmentioned above, each terminal can communicate with one or more basestations via transmissions on the forward and reverse links. The forwardlink (or downlink) refers to the communication link from the basestations to the terminals, and the reverse link (or uplink) refers tothe communication link from the terminals to the base stations. Thiscommunication link can be established via a single-in-single-out system,a MIMO system, or some other type of system.

The various illustrative logics, logical blocks, modules, components,and circuits described in connection with the embodiments disclosedherein may be implemented or performed with a general purpose processor,a digital signal processor (DSP), an application specific integratedcircuit (ASIC), a field programmable gate array (FPGA) or otherprogrammable logic device, discrete gate or transistor logic, discretehardware components, or any combination thereof designed to perform thefunctions described herein. A general-purpose processor may be amicroprocessor, but, in the alternative, the processor may be anyconventional processor, controller, microcontroller, or state machine. Aprocessor may also be implemented as a combination of computing devices,e.g., a combination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration. Additionally, at least oneprocessor may comprise one or more modules operable to perform one ormore of the steps and/or actions described above. An exemplary storagemedium may be coupled to the processor, such that the processor can readinformation from, and write information to, the storage medium. In thealternative, the storage medium may be integral to the processor.Further, in some aspects, the processor and the storage medium mayreside in an ASIC. Additionally, the ASIC may reside in a user terminal.In the alternative, the processor and the storage medium may reside asdiscrete components in a user terminal.

In one or more aspects, the functions, methods, or algorithms describedmay be implemented in hardware, software, firmware, or any combinationthereof. If implemented in software, the functions may be stored ortransmitted as one or more instructions or code on a computer-readablemedium, which may be incorporated into a computer program product.Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage medium may be anyavailable media that can be accessed by a computer. By way of example,and not limitation, such computer-readable media can comprise RAM, ROM,EEPROM, CD-ROM or other optical disk storage, magnetic disk storage orother magnetic storage devices, or any other medium that can be used tocarry or store desired program code in the form of instructions or datastructures and that can be accessed by a computer. Also, substantiallyany connection may be termed a computer-readable medium. For example, ifsoftware is transmitted from a website, server, or other remote sourceusing a coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared, radio,and microwave, then the coaxial cable, fiber optic cable, twisted pair,DSL, or wireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and Blu-ray disc where disks usually reproducedata magnetically, while discs usually reproduce data optically withlasers. Combinations of the above should also be included within thescope of computer-readable media.

While the foregoing disclosure discusses illustrative aspects and/orembodiments, it should be noted that various changes and modificationscould be made herein without departing from the scope of the describedaspects and/or embodiments as defined by the appended claims.Furthermore, although elements of the described aspects and/orembodiments may be described or claimed in the singular, the plural iscontemplated unless limitation to the singular is explicitly stated.Additionally, all or a portion of any aspect and/or embodiment may beutilized with all or a portion of any other aspect and/or embodiment,unless stated otherwise.

What is claimed is:
 1. A method for calibrating transmit power of afemto node, comprising: detecting a handover of a served user equipment(UE) from a femto node to another node; measuring an uplink receivedsignal strength indicator (RSSI) at the femto node over a plurality oftime periods based on the detecting the handover; and calibrating atransmit power of the femto node based on comparing the uplink RSSImeasured over the plurality of time periods.
 2. The method of claim 1,wherein the plurality of time periods comprise at least an initial timeperiod and a subsequent time period.
 3. The method of claim 2, whereinthe calibrating the transmit power of the femto node is based ondetermining that the uplink RSSI at the subsequent time period and theuplink RSSI at the initial time period are within a thresholddifference.
 4. The method of claim 1, wherein the measured uplink RSSIat each time period of the plurality of time periods corresponds to anaverage or filtered uplink RSSI value over the time period.
 5. Themethod of claim 1, wherein calibrating the transmit power of the femtonode comprises: detecting whether the uplink RSSI measured over theplurality of time periods indicating a steadily decreasing uplink RSSI;and in response to detecting no steadily decreasing uplink RSSI,calibrating the transmit power of the femto node at one or moreincrements.
 6. The method of claim 5, wherein the one or more incrementscomprise: one or more fixed increments, or one or more incrementsdetermined based on RSSI measurements.
 7. The method of claim 1, furthercomprising: modifying a computed calibration of the transmit power basedon a detected level of interference.
 8. The method of claim 2, whereinthe subsequent time period is determined as a fixed point in timefollowing the initial time period, or determined based on one or moredetected events.
 9. The method of claim 1, wherein detecting thehandover of the served UE from the femto node to another node comprises:obtaining at least one measurement report including information relatingto measurements of signal strength or quality of a list of base stationsfrom which the served UE receives signals; and determining a usagepattern of the served UE based at least one the at least one measurementreport.
 10. An apparatus for calibrating transmit power of a femto node,comprising: at least one processor configured to: detect a handover of aserved user equipment (UE) from a femto node to another node; measure anuplink received signal strength indicator (RSSI) at the femto node overa plurality of time periods based on the detecting the handover; andcalibrate a transmit power of the femto node based on comparing theuplink RSSI measured over the plurality of time periods; and a memorycoupled to the at least one processor.
 11. The apparatus of claim 10,wherein the plurality of time periods comprise at least an initial timeperiod and a subsequent time period, and wherein the at least oneprocessor calibrates the transmit power of the femto node based ondetermining that the uplink RSSI at the subsequent time period and theuplink RSSI at the initial time period are within a thresholddifference.
 12. The apparatus of claim 10, wherein the measured uplinkRSSI at each time period of the plurality of time periods corresponds toan average or filtered uplink RSSI value over the time period.
 13. Theapparatus of claim 10, wherein the at least one processor configured tocalibrate the transmit power of the femto node by: detecting whether theuplink RSSI measured over the plurality of time periods indicating asteadily decreasing uplink RSSI; and calibrating the transmit power ofthe femto node at one or more increments in response to determining nosteadily decreasing uplink RSSI.
 14. The apparatus of claim 13, whereinthe one or more increments comprise: one or more fixed increments, orone or more increments determined based on RSSI measurements.
 15. Theapparatus of claim 10, wherein the at least one processor is furtherconfigured to modify a computed calibration of the transmit power basedon a detected level of interference.
 16. The apparatus of claim 11,wherein the subsequent time period is determined as a fixed point intime following the initial time period, or determined based on one ormore detected events.
 17. An apparatus for calibrating transmit power ofa femto node, comprising: means for detecting a handover of a serveduser equipment (UE) from a femto node to another node; means formeasuring an uplink received signal strength indicator (RSSI) at thefemto node over a plurality of time periods based on the detecting thehandover; and means for calibrating a transmit power of the femto nodebased on comparing the uplink RSSI measured over the plurality of timeperiods.
 18. The apparatus of claim 17, wherein the plurality of timeperiods comprise at least an initial time period and a subsequent timeperiod, and wherein the means for calibrating calibrates the transmitpower of the femto node based on determining that the uplink RSSI at thesubsequent time period and the uplink RSSI at the initial time periodare within a threshold difference.
 19. The apparatus of claim 17,wherein the measured uplink RSSI at each time period of the plurality oftime periods corresponds to an average or filtered uplink RSSI valueover the time period.
 20. The apparatus of claim 17, wherein the meansfor calibrating the transmit power of the femto node comprise: means fordetecting whether the uplink RSSI measured over the plurality of timeperiods indicating a steadily decreasing uplink RSSI; and means forcalibrating the transmit power of the femto node at one or moreincrements in response to determining no steadily decreasing uplinkRSSI.
 21. The apparatus of claim 20, wherein the one or more incrementscomprise: one or more fixed increments, or one or more incrementsdetermined based on RSSI measurements.
 22. The apparatus of claim 17,further comprising: means for modifying a computed calibration of thetransmit power based on a detected level of interference.
 23. Theapparatus of claim 18, wherein the subsequent time period is determinedas a fixed point in time following the initial time period, ordetermined based on one or more detected events.
 24. A non-transitorycomputer-readable medium storing computer executable codes forcalibrating transmit power of a femto node, comprising: code for causingat least one computer to detect a handover of a served user equipment(UE) from a femto node to another node; code for causing the at leastone computer to measure an uplink received signal strength indicator(RSSI) at the femto node over a plurality of time periods based on thedetecting the handover; and code for causing the at least one computerto calibrate a transmit power of the femto node based on comparing theuplink RSSI measured over the plurality of time periods.
 25. Thecomputer-readable medium of claim 24, wherein the plurality of timeperiods comprise at least an initial time period and a subsequent timeperiod, and wherein the code for causing the at least one computer tocalibrate calibrates the transmit power of the femto node based ondetermining that the uplink RSSI at the subsequent time period and theuplink RSSI at the initial time period are within a thresholddifference.
 26. The computer-readable medium of claim 24, wherein themeasured uplink RSSI at each time period of the plurality of timeperiods corresponds to an average or filtered uplink RSSI value over thetime period.
 27. The computer-readable medium of claim 24, wherein thecode for causing the at least one computer to calibrate the transmitpower comprises code for: detecting whether the uplink RSSI measuredover the plurality of time periods indicating a steadily decreasinguplink RSSI; and calibrating the transmit power of the femto node at oneor more increments in response to detecting no steadily decreasinguplink RSSI.
 28. The computer-readable medium of claim 27, wherein theone or more increments comprise: one or more fixed increments, or one ormore increments determined based on RSSI measurements.
 29. Thecomputer-readable medium of claim 24, further comprising code forcausing the at least one computer to modify a computed calibration ofthe transmit power based on a detected level of interference.
 30. Thecomputer-readable medium of claim 25, wherein the subsequent time periodis determined as a fixed point in time following the initial timeperiod, or determined based on one or more detected events.